270_BMW,

The improved O-ring is thicker.
I used it and love it.
It is a tight fit and almost impossible to blow out under pressure.
Remember O-ring usually blows out because it is "under-sized" for the gap it tries to seal, or bc the pressure is too high for the design.

__________________
1998 E39 528i 5sp MT
2006 E53 X5 3.0 6sp MT